Freefall Activities Lab

Purpose: Find your reaction time (forward and peripheral), hang time and velocity that you can through a ball upward.

Materials: Ruler and stop watch

Procedure:

A. Reaction time:

1. The Dropper will hold a meter stick vertically between the thumb and index finger of the Catcher’s open hand. The meter stick should be held so that the zero mark is level with the tops of the Catcher’s fingers. The Catcher should not be touching the meters stick before it falls.
2. Without warning, the Dropper should release the meter stick so that it falls between the Catcher’s thumb and finger.
3. The Catcher should catch the meter stick as quickly as possible.
4. The Recorder writes down the distance, in centimeters, the meter stick fell through the Catcher’s fingers.
5. Repeat steps 1-4 until there is data for four to ten trials.
6. Do the same experiment but in the peripheral vision.
7. Switch roles and record data for the reaction times of the other group members.

B. Hang time

1. Measure the size of a brick and the mortar on a wall in centimeters and convert to meters.
2. Stand next to wall and measure starting brick height (without jumping)
3. The jumper will stand next to wall or take a "lay-up" and touch the wall as high as they can.
4. Count the number of bricks where they touched the wall.
5. The Recorder writes down the change in distance, in bricks, the Jumper from the standing to jumping height.
6. Repeat steps 1-4 until there is data for four-ten trials.
7. Switch roles and record data for the hang times of the other group members.

C. Up Velocity

1. Choose a ball and find a safe area to toss as high as possible
2. Throw the ball upward as high as possible (but don't injury yourself :)
3. The recorder should measure the time the ball is in the air from the moment it leaves the Thrower's hands until it returns to the same height.
4. The Recorder writes down the time in seconds, that the ball was in the air.
5. Repeat steps 1-4 until there is data for four- ten trials.
6. Switch roles and record data for the Up Velocity times of the other group members.

Data:

Reaction time:

Trial	Forward	Peripheral
1
2
3

Calculate average distance(m) Forward - m Peripheral - _m


Hang time - Height of one brick plus bottom mortar: cm and _m

Trial	Change in Number of bricks	Height (m) (# bricks x height of brick/mortar)
1
2
3

Calculate average change in height:

Up Velocity

Trial	Time ball in the air (s)
1
2
3

Calculate average time in air:

Calculations:

1. Calculate Average distance or time for each experiment.
2. Reaction time: Rearrange d = 1⁄2 gt2
   to solve for "t"
   d = the distance the meter stick fell, in meters (convert!!!)
   g = the acceleration of gravity, 9.81 m/s2
   t = the time the meter stick was falling
3. Hang time: Rearrange d = 1⁄2 gt2 to solve for "t". Substitute and solve and then MULTIPLY by 2 since hang time is both up and down.
4. Up Velocity - Divide the time by 2 since the time includes going up and the return. Use v = gt to solve for your velocity.

Questions:
1. Which reaction time was better - forward or peripheral? Why do you think it is this way?

2. Whose hang time was longer, yours or your partners? List at least three factors that could explain why different people have different hang times.

3. Micheal Jordan had the longest hang time of any NBA player at 0.92 seconds. What percent are you of his hang time?


4. How could you use the last experiment to find the kicking speed of a soccer player or the pitching speed of a softball or baseball pitcher?



Conclusion: Purpose, results, comments, errors